Molding die machining electrode, fabricating method of molding die, and molding die

Description

TECHNICAL FIELD

[0001] The present invention relates to a composite molding die machining electrode and a fabricating method of a molding die.

BACKGROUND ART

[0002] A molding die machining electrode has been proposed in that a plurality of hexagonal-columnar tubular bodies, each having a through-hole, are attached on a plate retainer arranged at one ends of the tubular bodies so as to have a predetermined space between them, and while the electrode is being moved by a predetermined distance in a direction perpendicular to the axes of the tubular bodies, pottery body forming grooves of an extrusion die are machined by electric discharging at several times so as to facilitate the fabrication of the molding die machining electrode as well as to reduce the fabrication period of time (see Japanese Unexamined Patent Application Publication No. 2001-71216, for example).

[0003] JP 2002 239 844 describes a method of manufacturing a honeycomb structure molding die using an electrode for electric spark machining. The electrode having an approximately polygonal shape.

DISCLOSURE OF THE INVENTION

[0004] However, in the molding die machining electrode described in Japanese Unexamined Patent Application Publication No. 2001-71216, the molding die is not integrally fabricated but is processed in several stages, so that the molding die machining electrode can be easily fabricated; however, the extrusion die grooves are processed by overlapping the grooves processed with the linearly arranged hexagonal-columnar tubular bodies by the electric discharging in several stages. Since the tubular bodies are linearly arranged, the overlapped grooves are also processed linearly or in grid-like. Since the width of the groove processed by overlapping is increased in comparison with the grooves otherwise processed, linearly or grid-like broad grooves may exist in the extrusion die. If a columnar molded body, for example, is molded using such an extrusion die, the molding material may be non-uniformly extruded so as to generate formed curvature.

[0005] The present invention has been made in view of such problems, and it is an object of the present invention to provide a composite molding die machining electrode and a fabricating method of a molding die.

[0006] In order to achieve the object described above, the present invention has adopted the following means.

[0007] According to one aspect, the present invention is directed to a composite molding die machining electrode as set out in claim 1.

[0008] In the composite molding die machining electrode, the slit grooves of the molding die are machined with the slit groove forming portion of the first electrode member having a circular or elliptical outer circumference; while the second electrode member formed coaxially with the first electrode member and having polygonal erected wall parts with a circular or elliptical inner circumference for machining the slit grooves overlaps with the slit grooves formed by the erected wall parts in the outer circumference of the slit groove forming portion of the first electrode member, the outside slit grooves formed by the first electrode member are machined with the slit groove forming portion of the second electrode member having a substantially circular outer circumference. In such a manner, since a plurality of the slit groove forming portion of the composite molding die machining electrode are radially divided, the electrode can be more easily fabricated in comparison with the fabrication of an integral electrode. Also, since overlapping portions between the plurality of the slit groove forming portion of the electrode members are formed substantially coaxially with a molded body, when the molded body is formed with the fabricated molding die, the formed curvature of the molded body can be further suppressed in comparison with a case where the overlapping portions between a plurality of the slit groove forming portion of the electrode members are formed in a rectangular lattice pattern or a linear shape. Herein, "overlaps with the slit grooves formed by the erected wall parts in the outer circumferential region of the slit groove forming portion of the first member" means that during fabricating the molding die, the slit grooves machined with the erected wall parts in the outer circumference of the slit groove forming portion of the first electrode member overlap with the slit grooves machined with the erected wall parts in the inner circumferential region of the slit groove forming portion of the second electrode member. In addition, the molding die machining electrode may include the two or more electrode members.

[0009] In the composite molding die machining electrode according to the present invention, preferably, the slit groove forming portion of the first electrode member is formed to have a circular or elliptical outer circumference by ranging the polygonal erected wall parts in a row, the slit groove forming portion of the second electrode member is formed to have a circular or elliptical shape such that the inner circumference of the erected wall parts of the slit groove forming portion of the second electrode member overlaps with the slit grooves machined with the outer circumference of the erected wall parts of the slit groove forming portion of the first electrode member while the second electrode member being formed to have a circular or elliptical outer circumference by ranging the polygonal erected wall parts in a row. By such a configuration, no imperfect polygon exists in the outer and inner circumferences of each electrode member, so that the misalignment of the slit grooves machined with the first and second electrode members can be suppressed.

[0010] In the composite molding die machining electrode according to the present invention, preferably, the first electrode member and the second electrode member are formed such that the end-face area of the slit groove forming portion of the first electrode member is the same as that of the slit groove forming portion of the second electrode member. By such a configuration, the unevenness in wear of the erected wall parts of each electrode member can be more suppressed, so that during fabrication of the molding die, accuracies in size in the depth direction can be improved. Since the areas are constant, the fabrication time becomes constant, so that accuracies in slit width can be improved. Furthermore, the time for electrode fabrication and slit machining becomes constant, also improving the productivity.

[0011] In the composite molding die machining electrode according to the present invention, preferably, the thickness of the polygonal erected wall part of the slit groove forming portion of the second electrode member is different from that of the erected wall part of the slit groove forming portion of the first electrode member. By such a configuration, since the first electrode member and the second electrode member are radially divided, a molding die having a width of a slit groove different in the radial direction can be easily fabricated. At this time, in the second electrode member, the thickness of the polygonal erected wall part may be larger than that of the first electrode member. By such a configuration, the thickness of the outer circumference of the molded body molded with the fabricated molding die becomes larger, so that the strength of the molded body can be increased. Alternatively, in the slit groove forming portion the second electrode member, the thickness of the polygonal erected wall part may be smaller than that of the slit groove forming portion the first electrode member.

[0012] In the molding die machining electrode according to the present invention, preferably, the slit groove forming portion the first electrode member is formed of the hexagonal erected wall parts, and the slit groove forming portion the second electrode member is formed of the hexagonal erected wall parts. By such a configuration, the mechanical strength of the molded body formed with the fabricated molding die can be increased when an external force is applied thereto.

[0013] In the invention of a fabricating method of a molding die for molding a molded body with a circular or elliptical outer circumference by extruding a molding material through slit grooves, the fabricating method including the steps; forming supply holes on a surface of a substrate for supplying the molding material; and machining the slit grooves communicated with the supply holes on the substrate using the composite molding die machining electrode.

[0014] In the fabricating method of a molding die, supply holes are formed on a surface of a substrate for supplying the molding material and then, the slit grooves communicated with the supply holes are machined on the substrate using any one form of the composite molding die machining electrode described above. In such a manner, since a plurality of electrode members of the composite molding die machining electrode are radially divided, the molding die can be more easily fabricated in comparison with the electrode members divided into rectangular lattice patterns or the electrode members linearly divided. Since the overlapping portion between the machined slit grooves are formed coaxially with the molded body, when the molded body is molded with the molding die, the formed curvature of the molded body can be further suppressed in comparison with a case where the overlapping portions between a plurality of the slit grooves are formed in a rectangular lattice pattern or a linear shape.

[0015] In the fabricating method of a molding die according to the present invention, preferably, the machining the slit grooves includes first slit grooves machining step for machining the slit grooves communicated with the supply holes on the substrate with the polygonal erected wall parts formed in the first electrode member; and second slit grooves machining step for machining on the substrate the slit grooves, which are communicated with the supply holes outside the slit grooves machined with the first electrode member, with the polygonal erected wall parts formed in the second electrode member such that the slit grooves machined with the outer circumference of the erected wall parts of the first electrode member overlap with the slit grooves to be machined with the inner circumference of the erected wall parts of the second electrode member. By such a manner, since the slit grooves are formed from the inner circumference toward the outer circumference, the slit groove machining process can be executed more easily. Alternatively, the machining the slit grooves may also include second slit grooves machining step for machining the slit grooves communicated with the supply holes on the substrate with the polygonal erected wall parts formed in the second electrode member; and first slit grooves machining step for machining on the substrate the slit grooves, which are communicated with the supply holes inside the slit grooves machined with the second electrode member, with the polygonal erected wall parts formed in the first electrode member such that the slit grooves machined with the inner circumference of the erected wall parts of the second electrode member overlap with the slit grooves to be machined with the outer circumference of the erected wall parts of the first electrode member.

[0016] The fabricating method of a molding die according to the present invention may further include the steps of machining the circumference of the substrate at a predetermined depth from the surface of the substrate and within a range of the slit grooves machined with the second electrode member after the slit grooves are machined along the outermost circumference of the substrate at the machining the slit grooves step; and removing foreign materials generated in the slit grooves at the machining the circumference step using the second electrode member. By such a manner, the removal of foreign materials after the circumference machining process may be executed with the second electrode member formed in the same shape as that of the member for machining the circumference, the number of removing operations with the electrode member in the foreign material removing process can be reduced in comparison with a case using a composite molding die machining electrode divided into rectangular lattice patterns or linear shapes. The "machining the circumference" herein may include cutting, electric discharge machining, electromechanical machining, laser machining, and drilling.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 

Figs. 1A to 1C are schematic structural views of a molding die machining electrode 10, in which Fig. 1A is an explanatory view of a first electrode 20, Fig. 1B a second electrode 30, and Fig. 1C a third electrode 40;

Figs. 2A to 2D are explanatory views of processes machining supply holes 52 and a slit groove part 54 on a substrate 51, in which Fig. 2A is an explanatory view of a process machining the supply holes, Fig. 2B a first process machining slit grooves, Fig. 2C a second process machining slit grooves, and Fig. 2D a third process machining slit grooves;

Figs. 3A to 3D are explanatory views of processes cutting and electric discharge machining a circumferential part 58 of the substrate 51, in which Fig. 3A is a sectional view of the substrate 51 after the third process machining slit grooves, Fig. 3B is an explanatory view of a process machining the circumferential part, Fig. 3C a process removing foreign materials, and Fig. 3D the molding die 50; and

Fig. 4 is an explanatory view of extrusion forming.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Then, most preferred embodiments according to the present invention will be described with reference to the drawings. Figs. 1A to 1C are schematic structural views of a composite molding die machining electrode 10 according to an embodiment, in which Fig. 1A is an explanatory view of a first electrode 20, Fig. 1B a second electrode 30, and Fig. 1C a third electrode 40. In Figs. 1A to 1C, each upper figure is a plan view; each middle figure a partial enlarged view; and each lower figure a sectional view. The composite molding die machining electrode 10, as shown in Figs. 1A to 1C, includes three electrode members of the first electrode 20, the second electrode 30, and the third electrode 40 for electric discharge machining a molding die electrode for use in extrusion molding a honeycomb carrier for cleaning up vehicle exhaust gas and a honeycomb filter removing fine particles. The number of electrode members in the composite molding die machining electrode 10 is not limited to a specific one as long as the number is two or more.

[0019] The first electrode 20, as shown in Fig. 1A, is a member for machining slit grooves at substantially the center of a substrate of the molding die, and made of a member for electric discharge machining (graphite, copper/tungsten, and copper, for example). The first electrode 20 includes a rectangular plate base 21 and a slit groove forming part 22 erected from the center of the base 21 for forming slit grooves on the substrate of the molding die. The slit groove forming part 22 is formed of polygonal erected wall parts 23 ranging in a row to have a substantially circular circumference. A hexagon is employed by the polygon of the erected wall part 23 having a space 24 with a hexagonal inside perimeter at its center. The erected wall part 23 has a thickness of d1 based on the wall thickness of the molded body molded using the molding die machined by the molding die machining electrode 10.

[0020] The second electrode 30 is a member for machining slit grooves around the slit grooves formed with the first electrode 20 on the substrate of the molding die, and made of a member for the electric discharge machining (graphite, copper/tungsten, and copper, for example). The second electrode 30 includes a rectangular plate base 31 and a slit groove forming part 32 erected cylindrically about the center of the base 31 and forms slit grooves on the substrate of molding die. The slit groove forming part 32 is formed of polygonal erected wall parts 33 ranging in rows about the same axis as that of the first electrode 20 to have a substantially circular shape with its inside circumference overlapping with the outside circumference of the slit grooves formed with the outer circumference of the erected wall parts 23 in the first electrode 20 as well as the slit groove forming part 32 has a substantially outer circular circumference by ranging the polygonal erected wall parts 33. Namely, the erected wall parts 33 are formed such that during machining the molding die, the slit grooves machined with the erected walls 23 in the outer circumference of the first electrode 20 overlap with the slit grooves machined with the erected wall parts 33 in the inner circumference of the second electrode 30. The erected wall part 33 is shaped in a hexagon and has a space 34 with a hexagonal inside perimeter at its center. The erected wall part 33 also has a thickness of d2, larger than d1, based on the wall thickness of the molded body molded using the molding die machined by the molding die machining electrode 10. The second electrode 30 is provided with a through part 35, which is a circular through-hole, formed at the center.

[0021] The third electrode 40 is a member for machining slit grooves around the slit grooves formed with the second electrode 30 on the substrate of the molding die, and made of a member for the electric discharge machining (graphite, copper/tungsten, and copper, for example). The third electrode 40 includes a rectangular plate base 41 and a slit groove forming part 42 erected cylindrically about the center of the base 41 and forms slit grooves on the substrate of the molding die. The slit groove forming part 42 is formed of polygonal erected wall parts 43 ranging in rows about the same axis as those of the first electrode 20 and the second electrode 30 to have a substantially circular shape with its inside circumference overlapping with the outside circumference of the slit grooves formed with outer circumferences of the erected wall parts 33 in the second electrode 30 as well as the slit groove forming part 42 has a substantially circular outer circumference by ranging the polygonal erected wall parts 43. Namely, the erected wall parts 43 are formed such that during machining the molding die, the slit grooves machined with the erected wall parts 33 in the outer circumference of the second electrode 30 overlap with the slit grooves machined with the erected wall parts 43 in the inner circumference of the third electrode 40. The erected wall part 43 is shaped in a hexagon and has a space 44 with a hexagonal inside perimeter at its center. The erected wall part 43 has a thickness of d3, larger than d2, based on the wall thickness of the molded body molded using the molding die machined by the molding die machining electrode 10. The erected wall parts 43 are also formed to have a diameter one-size larger than that for forming the molded body with the molding die. The third electrode 40 is provided with a through part 45, which is a circular through-hole, formed at the center.

[0022] In the composite molding die machining electrode 10, the slit groove forming parts 22, 32, and 42 are formed such that the slit groove forming parts 22, 32, and 42 of the first to third electrodes 20, 30, and 40 have respective nearer areas. It is more preferable that the slit groove forming parts 22, 32, and 42 have the same area; however, if the respective areas are not equalized due to the total area of the molding die 50, the respective polygon areas of the erected wall parts 23, 33, and 43, and the thicknesses d1, d2, and d3, it is preferable that the respective areas be designed closer to each other.

[0023] Then, the operation for machining the molding die 50 with the composite molding die machining electrode 10 configured in such a manner will be described. The fabrication of the molding die 50 includes: (1) a supply hole machining process for perforating the substrate to have supply holes for supplying a forming material therethrough; (2) a slit groove machining process for machining slit grooves communicating with the supply holes with the molding die machining electrode 10; (3) a circumference machining process for cutting or electric discharge machining a circumferential part of the substrate at a predetermined depth and within a range of the slit grooves fabricated along the outermost circumference; and (4) a foreign material removing process for removing foreign materials generated by the circumference machining process in the slit grooves. Figs. 2A to 2D are explanatory views of processes machining supply holes 52 and a slit groove part 54 on a substrate 51, in which Fig. 2A is an explanatory view of a process machining the supply holes, Fig. 2B a first process machining slit grooves, Fig. 2C a second process machining slit grooves, and Fig. 2D a third process machining slit grooves. Figs. 3A to 3D are explanatory views of processes cutting and electric discharge machining a circumferential part 58 of the substrate 51, in which Fig. 3A is a sectional view of the substrate 51 after the third process machining slit grooves, Fig. 3B is an explanatory view of a process machining the circumferential part, Fig. 3C a process removing foreign materials, and Fig. 3D the molding die 50. In Figs. 2A to 2D, each upper figure is a sectional view of each electrode; each middle figure a plan view of the substrate 51; and each lower figure a partial enlarged view of the substrate 51.

(1) Supply hole machining process
The substrate 51 is prepared as a base of the molding die. A disk or a sectoral plate with a diameter one size larger than that of the molding die (stainless steal or cemented carbide) is used. As shown in Fig. 2A, the upper surface of the substrate 51 is perforated with liquid holes 52a for forming slit grooves while the bottom surface of the substrate 51 being perforated with supply holes 52, each larger than the liquid hole 52a, formed on a supply hole forming region 51a. The perforation with the liquid holes 52a and the supply holes 52 may be executed by electromechanical machining, electric discharge machining, laser machining, or drilling, for example. The liquid holes 52a and the supply holes 52 are formed at positions where they communicate with the slit grooves that will be formed later, herein, at three points among apexes of each hexagon of the slit grooves. The substrate 51 is also perforated with fixing holes 53 that are through-holes formed at ends of the substrate 51 for fixing the substrate 51 with bolts.

(2) Slit groove machining process
Then, using an electric discharge machine (not shown), a slit groove part 54 is formed with the molding die machining electrode 10 on the upper surface of the substrate 51 where the liquid holes 52a are formed. The slit groove machining process herein includes first slit groove machining with the first electrode 20, second slit groove machining with the second electrode 30, and third slit groove machining with the third electrode 40 to be executed sequentially in that order. In the electric discharge machining, a voltage with a predetermined pulse is applied across between the substrate 51 and the slit groove forming parts 22, 32, and 42 serving as machining electrodes so as to generate sparks between them for machining the surface of the substrate 51. The electric discharge machining herein has three sets of rough processing, depth finishing, and width finishing that are executed using the electrodes 20, 30, and 40, respectively; alternatively, the slit groove part 54 may also be finished with one set of the electrode or with two or more optional sets of the electrodes. First, while the substrate 51 is being fixed with its upper surface directed upward to the electric discharge machine, the first electrode 20, with its slit groove forming part 22 directed downwardly, is fixed on the substrate 51 for machining a first slit groove part 54a of the substrate 51. When electric discharge machining using the first electrode 20, as shown in the lower figure of Fig. 2B, first slit grooves 55 communicated with the supply holes 52 are formed with the erected wall parts 23 (see Fig. 1A). Then, as shown Fig. 2C, the electric discharge machining is executed using the second electrode 30. In the second slit groove machining process, while the second electrode 30 is arranged coaxially with the first electrode 20, the electric discharge machining is executed by fixing the second electrode 30 such that the first slit grooves 55 machined with the erected wall parts 23 in the outer circumference of the first electrode 20 overlap with second slit grooves 56 to be machined with the erected wall parts 33 in the inner circumference of the second electrode 30. Since the thickness d2 of the erected wall part 33 is larger than the thickness d1 of the erected wall part 23, the second electrode 30 is arranged such that the first slit grooves 55 are included in the second slit grooves 56. When electric discharge machining in such a manner, as shown in the lower figure of Fig. 2C, the second slit grooves 56 communicated with the supply holes 52 are formed with the erected wall parts 33 (see Fig. 1B). Subsequently, as shown in Fig. 2D, the electric discharge machining is executed using the third electrode 40. In the third slit groove machining process, while the third electrode 40 is arranged coaxially with the first electrode 20 and the second electrode 30, the electric discharge machining is executed by fixing the third electrode 40 such that the second slit grooves 56 machined with the erected wall parts 33 in the outer circumference of the second electrode 30 overlap with third slit grooves 57 to be machined with the erected wall parts 43 in the inner circumference of the third electrode 40. Since the thickness d3 of the erected wall part 43 is larger than the thickness d2 of the erected wall part 33, the third electrode 40 is arranged such that the second slit grooves 56 are included in the third slit grooves 57. When electric discharge machining in such a manner, as shown in the lower figure of Fig. 2D, the third slit grooves 57 communicated with the supply holes 52 are formed with the erected wall parts 43 (see Fig. 1C). By the slit groove machining process in such a manner, overlapping portions of the slit groove part 54 are formed substantially coaxially in the same way of a molded body 70 while the slit groove part 54 is formed such that the width of the slit groove is increased with increasing circumference. The case of the three electrodes has been described herein; when the number of the electrodes is four or more, the processing described above may be repeated.

(3) Circumference machining process
Then, as shown in Figs. 3A and 3B, for arranging the molding die in shape at its outer circumferential end, a circumferential part 58, which is a range including a part slit at a predetermined depth from the surface of the substrate 51, of the substrate 51 is subjected to a circumference machining process with cutting or electric discharge machining. The circumference machining process may be executed prior to the slit groove machining process; however, since the end of a third slit groove part 54c becomes different in height, so that the third slit grooves 57 have the difference in depth due to the difference in wear of the erected wall part 43, the circumference machining process herein is executed after the slit groove machining process. When the circumferential part 58 is machined by the circumference machining process, it may be executed by electromechanical machining, electric discharge machining, laser machining, or drilling.

(4) Foreign material removing process
Subsequently, as shown in Fig. 3C, foreign materials (burrs, for example) generated in the third slit groove part 54c by the circumference machining process are removed. The removing of the foreign materials is executed on the third slit groove part 54c, which is the circumferential part 58 machined by cutting or electric discharge machining, by the third slit groove machining process using the slit groove forming part 42 of the third electrode 40. If the slit groove herein is machined using a rectangular electrode for example, while the circumferential part 58, which is cut or electric discharge machined, is circular, the electrode is rectangular to have a different shape, so that it is necessary to remove the foreign materials at several times using the electrode. The third electrode 40 and the circumferential part 58 herein have the same shape that is radially divided, so that even when the circumferential part 58 has been cut or electric discharge machined, the removing of the foreign materials can be once executed by the slit groove machining process using the third electrode 40. Through such steps, the molding die 50 shown in Fig. 3D can be machined.

[0024] Then, as shown in Fig. 4, while a disk-shaped fixed plate (not shown) is being set at the circumferential part 58, the molding die 50 is fixed at the end of an extruder 60; a forming material is supplied to the extruder 60 via its supply holes 52 for extrusion forming by pressurizing the forming material. Fig. 4 is an explanatory view of the extrusion forming. In such a manner, the extrusion forming is executed using the molding die 50 machined with the erected wall parts 23, each having a thickness of d1 of the molding die machining electrode 10, the erected wall parts 33, each having a thickness of d2, and the erected wall parts 43, each having a thickness of d3, so that a molded body 70 can be molded having a first region 72, a second region 74, and a third region 76, i.e., having wall thicknesses increasing with increasing circumference. Then, through a drying process, a burning process, and a catalyst carrying process, the molded body 70 is used for a honeycombed structure.

[0025] According to the molding die machining electrode 10 of the embodiment described in detail as above, while the first slit grooves 55 are formed with the slit groove forming part 22 formed of the hexagonal erected wall parts 23 ranging in a row to have a substantially circular outer circumference, the slit grooves on the outside of the first slit groove part 54a formed with the first electrode 20 are machined with the slit groove forming part 32 arranged coaxially with the slit groove forming part 22, which is formed of the hexagonal erected wall parts 33 to have a substantially circular inner circumference and to overlap with the erected wall parts 23 on the outer circumference of the slit groove forming part 22 as well as to have a substantially outer circular circumference. Similarly, the slit grooves on the outside of a second slit groove part 54b formed with the second electrode 30 are machined with the erected wall parts 43 of the third electrode 40. Since a plurality of slit groove forming parts are radially divided in such a manner, the composite molding die machining electrode 10 can be more easily fabricated in comparison with the fabrication of an integral molding die machining electrode. The overlapping portions between a plurality of the slit groove forming parts are formed substantially coaxially with the molded body, so that when the molded body is formed with the fabricated molding die 50, the formed curvature of the molded body can be further suppressed in comparison with a case where the overlapping portions between a plurality of the slit groove forming parts are formed in a rectangular lattice pattern or a linear shape. Since the hexagonal erected wall parts 23, 33, and 43 are ranged in rows, their outer or inner circumferences are substantially circular, so that imperfect polygons do not exist in the outer or inner circumference of each slit groove forming part, suppressing the misalignment in slit grooves formed by the slit groove forming parts. Since the first to third electrodes 20 to 40 are configured such that the slit groove forming parts 22, 32, and 42 have respective areas closer to each other, the unevenness in wear of the erected wall parts 23, 33, and 43 of the slit groove forming parts 22, 32, and 42 can be more suppressed, so that during fabrication of the molding die 50, accuracies in size in the depth direction can be improved and variations in slit width can be also reduced. Since the areas are constant, variations in fabrication time can be suppressed, so that the time for electrode fabrication, i.e., slit machining, becomes constant, improving the productivity. Furthermore, since the thickness of the erected wall part is increased with increasing circumference, in the order of the erected wall parts 23, 33, and 43, the strength of the formed molded body 70 can be increased, facilitating the molded body 70 to be fabricated. Since the first to third electrodes 20 to 40 are also configured such that the hexagonal erected wall parts 23, 33, and 43 are ranged in rows, respectively, the mechanical strength of the molded body 70 formed with the fabricated molding die 50 can be increased when an external force is applied thereto.

[0026] According to the fabrication method of the molding die 50, since a plurality of the slit groove forming parts of the molding die machining electrode 10 are radially divided, the molding die 50 can be more easily fabricated in comparison with slit groove forming parts divided into rectangular lattice patterns or linear shapes. The overlapping portions of the fabricated slit groove part 54 are formed substantially coaxially with the molded body 70, so that when the molded body 70 is formed with the molding die 50, the formed curvature of the molded body can be further suppressed in comparison with a case where the overlapping portions between a plurality of the slit groove are formed in a rectangular lattice pattern or a linear shape. Since the slit groove part 54 is formed from the inner circumference toward the outer circumference in the order of the first to third electrodes 20 to 40, the slit groove machining process can be executed more easily. Furthermore, since the removal of foreign materials generated by the circumferential machining process may be performed with the third electrode 40 having the same shape as that of the circumferentially machined body, the number of removing operations with the slit groove forming part in the foreign material removing process can be reduced in comparison with a case using a molding die machining electrode divided into rectangular lattice patterns or linear shapes. Also, the molded body 70 formed with the molding die 50 fabricated in such a manner is molded using the molding die 50 machined with the molding die machining electrode 10 described above, facilitating the molded body 70 to be fabricated as well as suppressing formed curvature.

[0027] The correspondence relationship between the components according to the embodiment and those according to the present invention is explained herein. The slit groove forming part 22 according to the embodiment corresponds to a first forming member, and the slit groove forming part 32 corresponds to a second forming member. If the slit groove forming part 32 corresponds to a first forming member, the slit groove forming part 42 corresponds to a second forming member.

[0028] The present invention is not limited to the embodiment described above, so that various modifications can be obviously made within the scope of the claims.

[0029] For example, according to the embodiment described above, the slit groove forming parts 22, 32, and 42 are formed such that the respective areas of the erected wall parts 23, 33, and 43 are close to each other; however, the invention is not limited to this, so that the areas may not be close to each other. Even in such a manner, the composite molding die machining electrode 10 and the molding die 50 can be easily fabricated while the formed curvature of the molded body 70 can be suppressed when the molded body 70 is molded with the molding die 50.

[0030] According to the embodiment described above, the respective thicknesses of the erected wall parts 23, 33, and 43 are increased toward the outer circumference in that order; however, the thicknesses of the erected wall parts 23, 33, and 43 may be the same. Alternatively, the thicknesses of the erected wall parts 23, 33, and 43 may be decreased toward the outer circumference in that order; and the respective thicknesses may be designed as having appropriately arbitrary values. They may be appropriately designed in accordance with characteristics and performances of the molded body 70.

[0031] According to the embodiment described above, the slit groove part 54 is formed from the inner circumference toward the outer circumference in the order of the first electrode 20, the second electrode 30, and the third electrode 40; however, the invention is not limited to this, so that the slit groove part 54 may also be formed from the outer circumference toward the inner circumference in the order of the third electrode 40, the second electrode 30, and the first electrode 20; and the slit groove part 54 may also be formed in a random order. Even in such a manner, the composite molding die machining electrode 10 and the molding die 50 can be easily fabricated while the formed curvature of the molded body 70 can be suppressed when the molded body 70 is molded with the molding die 50.

[0032] According to the embodiment described above, in the slit groove forming parts 22, 32, and 42, by ranging the hexagonal erected wall parts 23, 33, and 43 in rows, the outer and inner circumferences of the erected wall parts are formed in substantially circular shapes; however, the invention is not specifically limited to this, so that part or the entire of the hexagonal erected wall parts 23, 33, and 43 may not be ranged and the outer and inner circumferences of the erected wall parts may also be formed in substantially circular shapes. Namely, an imperfect hexagon (one or more sides with one not-connected end exist) may be formed in the outer and inner circumferences of the slit groove forming parts 22, 32, and 42. Even in such a manner, the composite molding die machining electrode 10 and the molding die 50 can be easily fabricated while the formed curvature of the molded body 70 can be suppressed when the molded body 70 is molded with the molding die 50.

[0033] According to the embodiment described above, the circumference machining process and the removal of foreign materials process are executed after the slit groove machining process; alternatively, they may be executed prior to the slit groove machining process or the circumference machining process and the removal of foreign materials process may also be omitted.

[0034] According to the embodiment described above, the erected wall parts 23, 33, and 43 are ranged in hexagonal shapes; the invention is not limited to this as long as they are polygonal, so that a triangle, a square, an octagon, and a dodecagon may be adopted. At this time, the polygonal wall parts may be ranged so that contours of the slit groove forming parts 22, 32, and 42 become circular as closely to the contour shape of the molded body 70 as possible.

[0035] This application is filed by claiming the priority of Japanese Patent Application No. 2007-244063 filed on 20th September, 2007.

Claims

1. A composite molding die machining electrode (10) for use in fabricating an extrusion molding die (51) which has slit grooves (55, 56, 57) for forming a molded body (52) having a circular or elliptical outer circumference, said composite electrode having plural electrode members (20, 30) to be used sequentially in forming said slit grooves of the die, said electrode members comprising:

a first electrode member (20) with a slit groove forming portion (22) having polygonal erected wall parts (23) for machining said slit grooves (55) and having a circular or elliptical outer circumference, and

a second electrode member (30) with a slit groove forming portion (32) having polygonal erected wall parts (33) for machining said slit grooves (56) and having a circular or elliptical outer circumference and a circular or elliptical inner circumference,

wherein when said first and second members (20, 30) are employed sequentially in a coaxial arrangement to form said slit grooves in an extrusion molding die, an inner circumferential region of the slit groove forming portion (32) of the second member (30) overlaps an outer circumferential region of the slit groove forming portion (22) of the first member (20).

2. The composite molding die machining electrode (10) according to Claim 1, wherein the slit groove forming portion (22) of the first electrode member (20) is formed to have a circular or elliptical outer circumference by ranging the polygonal erected wall parts (23) in rows, and the slit groove forming portion (32) of the second electrode member (30) is formed to have a circular or elliptical shape by ranging the polygonal erected wall parts (33) in rows;
the slit groove forming portion (32) of the second electrode member (30) being formed to have a circular or elliptical inner circumference by ranging the polygonal erected wall parts (33) in rows and the slit groove forming portion (32) of the second electrode member (30) being formed to have a circular or elliptical outer circumference by ranging the polygonal erected wall parts (33) in rows.

3. The composite molding die machining electrode (10) according to Claim 1 or 2, wherein the first electrode member (20) and the second electrode member (30) are formed such that the end-face area of the slit groove forming portion (22) of the first electrode member (20) is the same as that of the slit groove forming portion (32) of the second electrode member (30).

4. The composite molding die machining electrode (10) according to any one of Claims 1 to 3, wherein the thickness of the polygonal erected wall part (33) of the slit groove forming portion (32) of the second electrode member (30) is different from that of the erected wall part (33) of the slit groove forming portion (22) of the first electrode member (20).

5. The composite molding die machining electrode (10) according to Claim 4, wherein the thickness of the polygonal erected wall part (33) of the slit groove forming portion (32) of the second electrode member (30) is larger than that of the erected wall part (33) of the slit groove forming portion (22) of the first electrode member (20).

6. The composite molding die machining electrode (10) according to any one of Claims 1 to 5, wherein the slit groove forming portion (22) of the first electrode member (20) is formed of the hexagonal erected wall parts (33), and the slit groove forming portion (32) of the second electrode member (30) is formed of the hexagonal erected wall parts (33).

7. A fabricating method of a molding die for molding a molded body with a circular or elliptical outer circumference by extruding a molding material through slit grooves, the fabricating method comprising the steps of:

forming supply holes on a surface of a substrate for supplying the molding material; and

machining the slit grooves communicated with the supply holes on the substrate using the composite molding die machining electrode according to any one of Claims 1 to 6.

8. The method according to Claim 7, wherein the machining the slit grooves includes:

first slit grooves machining step for machining the slit grooves communicated with the supply holes on the substrate with the polygonal erected wall parts (23) formed in the first electrode member (20); and

second slit grooves machining step for machining on the substrate the slit grooves, which are communicated with the supply holes outside the slit grooves machined with the first electrode member (20), with the polygonal erected wall parts (33) formed in the second electrode member (30) such that the slit grooves machined with the outer circumference of the erected wall parts (33) of the first electrode member (20) overlap with the slit grooves to be machined with the inner circumference of the erected wall parts (33) of the second electrode member (30).

9. The method according to Claim 7, wherein the machining the slit grooves includes:

second slit grooves machining step for machining the slit grooves communicated with the supply holes on the substrate with the polygonal erected wall parts (33) formed in the second electrode member (30); and

first slit grooves machining step for machining on the substrate the slit grooves, which are communicated with the supply holes inside the slit grooves machined with the second electrode member (30), with the polygonal erected wall parts (23) formed in the first electrode member (20) such that the slit grooves machined with the inner circumference of the erected wall parts (33) of the second electrode member (30) overlap with the slit grooves to be machined with the outer circumference of the erected wall parts (23) of the first electrode member (20).

10. The method according to any one of Claims 7 to 9, further comprising the steps of:

machining the circumference of the substrate at a predetermined depth from the surface of the substrate and within a range of the slit grooves machined with the second electrode member (30) after the slit grooves are machined along the outermost circumference of the substrate at the machining the slit grooves step; and

removing foreign materials generated in the slit grooves at the machining the circumference step using the second electrode member (30).

Ansprüche

1. Formwerkzeugbearbeitungsverbundelektrode (10) zur Verwendung bei der Herstellung eines Extrusionsformwerkzeugs (51), das Schlitznuten (55, 56, 57) zum Bilden eines geformten Körpers (52) mit einem kreisförmigen oder elliptischen Außenumfang, umfasst, wobei die Verbundelektrode mehrere Elektrodenelemente (20, 30) aufweist, die bei dem Bilden der Schlitznuten der Form sequenziell zu verwenden sind, wobei die Elektrodenelemente Folgendes umfassen:

ein erstes Elektrodenelement (20) mit einem Schlitznut-bildenden Abschnitt (22) mit polygonal errichteten Wandteilen (23) zur Herstellung der Schlitznuten (55) und mit einem kreisförmigen oder elliptischen Außenumfang, und

ein zweites Elektrodenelement (39) mit einem Schlitznut-bildenden Abschnitt (32) mit polygonal errichteten Wandteilen (33) zur Herstellung der Schlitznuten (56) und mit einem kreisförmigen oder elliptischen Außenumfang und einem kreisförmigen oder elliptischen Innenumfang,

worin, wenn die ersten und zweiten Elemente (20, 30) in einer koaxialen Anordnung sequenziell eingesetzt werden, um die Schlitznuten in einer Strangpressform zu bilden, ein Innenumfangsbereich des Schlitznut-bildenden Abschnitts (32) des zweiten Elements (30) einen Außenumfangsbereich des Schlitznut-bildenden Abschnitts (22) des ersten Elements (20) überlappt.

2. Formwerkzeugbearbeitungsverbundelektrode (10) nach Anspruch 1, worin der Schlitznut-bildende Abschnitt (22) des ersten Elektrodenelements (20) so ausgebildet ist, dass er einen kreisförmigen oder elliptischen Außenumfang hat, indem die polygonal errichteten Wandteile (23) in Reihen angeordnet sind, und der Schlitznut-bildende Abschnitt (32) des zweiten Elektrodenelements (30) so ausgebildet ist, dass er eine kreisförmige oder elliptische Form aufweist, indem die polygonal errichteten Wandteile (33) in Reihen angeordnet sind;
wobei der Schlitznut-bildende Abschnitt (32) des zweiten Elektrodenelements (30) so ausgebildet ist, dass er einen kreisförmigen oder elliptischen Innenumfang hat, indem die polygonal errichteten Teile (33) in Reihen angeordnet sind, und der Schlitznut-bildende Abschnitt (32) des zweiten Elektrodenelements (30) so ausgebildet ist, dass er einen kreisförmigen oder elliptische Außenumfang aufweist, indem die polygonal errichteten Teile (33) in Reihen angeordnet sind.

3. Formwerkzeugbearbeitungsverbundelektrode (10) nach Anspruch 1 oder 2, worin das erste Elektrodenelement (20) und das zweite Elektrodenelement (30) so ausgebildet sind, dass der Stirnflächenbereich des Schlitznut-bildenden Abschnitts (22) des ersten Elektrodenelements (20) derselbe ist wie der des Schlitznut-bildenden Abschnitts (32) des zweiten Elektrodenelements (30).

4. Formwerkzeugbearbeitungsverbundelektrode (10) nach einem der Ansprüche 1 bis 3, worin die Dicke des polygonal errichteten Wandteils (33) des Schlitznut-bildenden Abschnitts (32) des zweiten Elektrodenelements (30) sich von dem des errichteten Wandteils (33) des Schlitznut-bildenden Abschnitts (22) des ersten Elektrodenelements (20) unterscheidet.

5. Formwerkzeugbearbeitungsverbundelektrode (10) nach Anspruch 4, worin die Dicke des polygonal errichteten Wandteils (33) des Schlitznut-bildenden Abschnitts (32) des zweiten Elektrodenelements (30) größer ist als die des errichteten Wandteils (33) des Schlitznut-bildenden Abschnitts (22) des ersten Elektrodenelements (20).

6. Formwerkzeugbearbeitungsverbundelektrode (10) nach einem der Ansprüche 1 bis 5, worin der Schlitznut-bildende Abschnitt (22) des ersten Elektrodenelements (20) aus den hexagonal errichteten Wandteilen (33) ausgebildet ist und der Schlitznut-bildende Abschnitt (32) des zweiten Elektrodenelements (30) aus den hexagonal errichteten Wandteilen (33) errichtet ist.

7. Herstellungsverfahren für ein Formwerkzeug zum Formen eines geformten Körpers mit einem kreisförmigen oder elliptischen Außenumfang durch Extrusion eines Formmaterials durch Schlitznuten, wobei das Herstellungsverfahren folgende Schritte umfasst:

Ausbilden von Zuführungslöchern auf einer Oberfläche eines Substrats, um das Formmaterial zuzuführen; und

Bearbeiten der Schlitznuten, die mit den Zuführungslöchern auf dem Substrat verbunden sind, unter Verwendung der der Formwerkzeugbearbeitungsverbundelektrode nach einem der Ansprüche 1 bis 6.

8. Verfahren nach Anspruch 7,worin das Bearbeiten der Schlitznuten Folgendes umfasst:

einen ersten Schlitznutbearbeitungsschritt zum Bearbeiten der Schlitznuten, die mit den Zuführungslöchern auf dem Substrat mit den in dem ersten Elektrodenelement (20) ausgebildeten polygonal errichteten Wandteilen (23) kommunizieren; und

einen zweiten Schlitznutbearbeitungsschritt zum Bearbeiten der Schlitznuten auf dem Substrat, die mit den Zuführungslöchern außerhalb der Schlitznuten kommunizieren, die mit dem ersten Elektrodenelement (20) bearbeitet werden, wobei die in dem ersten Elektrodenelement (20) ausgebildeten polygonal errichteten Wandteile (33) derart ausgebildet sind, dass die mit dem Außenumfang der errichteten Wandteile (33) des ersten Elektrodenelements (20) bearbeiteten Schlitznuten und die mit dem Innenumfang der errichteten Wandteile (33) des zweiten Elektrodenelements (30) zu bearbeitenden Schlitznuten einander überlappen.

9. Verfahren nach Anspruch 7, worin das Bearbeiten der Schlitznuten Folgendes umfasst:

einen zweiten Schlitznutbearbeitungsschritt zum Bearbeiten der Schlitznuten, die mit den Zuführungslöchern auf dem Substrat mit den in dem ersten Elektrodenelement (30) ausgebildeten polygonal errichteten Wandteilen (33) kommunizieren; und

einen ersten Schlitznutbearbeitungsschritt zum Bearbeiten der Schlitznuten auf dem Substrat, die mit den Zuführungslöchern innerhalb der Schlitznuten kommunizieren, die mit dem zweiten Elektrodenelement (30) bearbeitet werden, wobei die in dem ersten Elektrodenelement (20) ausgebildeten polygonal errichteten Wandteile (23) derart ausgebildet sind, dass die mit dem Innenumfang der errichteten Wandteile (33) des zweiten Elektrodenelements (30) bearbeiteten Schlitznuten und die mit dem Außenumfang der errichteten Wandteile (23) des ersten Elektrodenelements (20) zu bearbeitenden Schlitznuten einander überlappen.

10. Verfahren nach einem der Ansprüche 7 bis 9, wobei das Verfahren ferner folgende Schritte umfasst:

Bearbeiten des Umfangs des Substrats in einer vorbestimmten Tiefe unter der Oberfläche des Substrats und innerhalb eines Bereichs der mit dem zweiten Elektrodenelement (30) bearbeiteten Schlitznuten, nachdem die Schlitznuten entlang des äußersten Umfangs des Substrats im Schlitznutbearbeitungsschritt bearbeitet wurden; und

Entfernen fremder Materialien, die in den Schlitznuten im Umfangsbearbeitungsschritt unter Verwendung des zweiten Elektrodenelements (30) entstanden sind.

Revendications

1. Electrode composée d'usinage de matrice de moulage (10) destinée à la fabrication d'une matrice de moulage par extrusion (51) dotée de rainures en forme de fente (55, 56, 57) pour former un corps moulé (52) ayant une circonférence externe circulaire ou elliptique, ladite électrode composée ayant plusieurs éléments d'électrode (20, 30) destinés à être utilisés successivement pour former lesdites rainures en forme de fente de la matrice, lesdits éléments d'électrode comprenant :

un premier élément d'électrode (20) doté d'une partie formation de rainure en forme de fente (22) ayant des éléments de paroi verticaux polygonaux (23) pour usiner lesdites rainures en forme de fente (55) et ayant une circonférence externe circulaire ou elliptique, et

un second élément d'électrode (30) doté d'une partie formation de rainure en forme de fente (32) ayant des éléments de paroi verticaux polygonaux (33) pour usiner lesdites rainures en forme de fente (56) et ayant une circonférence externe circulaire ou elliptique et une circonférence interne circulaire ou elliptique,

dans laquelle lesdits premier et second éléments (20, 30) sont employés successivement dans un agencement coaxial pour former lesdites rainures en forme de fente dans une matrice de moulage par extrusion, une région circonférentielle interne de la partie formation de rainure en forme de fente (32) du second élément (30) chevauche une région circonférentielle externe de la partie formation de rainure en forme de fente (22) du premier élément (20).

2. Electrode composée d'usinage de matrice de moulage (10) selon la revendication 1, dans laquelle la partie formation de rainure en forme de fente (22) du premier élément d'électrode (20) est formée de manière à avoir une circonférence externe circulaire ou elliptique par disposition des éléments de paroi verticaux polygonaux (23) en rangées, et la partie formation de rainure en forme de fente (32) du second élément d'électrode (30) est formée de manière à avoir une forme circulaire ou elliptique par disposition des éléments de paroi verticaux polygonaux (33) en rangées ;
la partie formation de rainure en forme de fente (32) du second élément d'électrode (30) étant formée de manière à avoir une circonférence interne circulaire ou elliptique par disposition des éléments de paroi verticaux polygonaux (33) en rangées et la partie formation de rainure en forme de fente (32) du second élément d'électrode (30) étant formée de manière à avoir une circonférence externe circulaire ou elliptique par disposition des éléments de paroi verticaux polygonaux (33) en rangées.

3. Electrode composée d'usinage de matrice de moulage (10) selon la revendication 1 ou 2, dans laquelle le premier élément d'électrode (20) et le second élément d'électrode (30) sont formés de sorte que la zone de face d'extrémité de la partie formation de rainure en forme de fente (22) du premier élément d'électrode (20) est identique à celle de la partie formation de rainure en forme de fente (32) du second élément d'électrode (30).

4. Electrode composée d'usinage de matrice de moulage (10) selon l'une quelconque des revendications 1 à 3, dans laquelle l'épaisseur de l'élément de paroi vertical polygonal (33) de la partie formation de rainure en forme de fente (32) du second élément d'électrode (30) est différente de celle de l'élément de paroi vertical (33) de la partie formation de rainure en forme de fente (22) du premier élément d'électrode (20).

5. Electrode composée d'usinage de matrice de moulage (10) selon la revendication 4, dans laquelle l'épaisseur de l'élément de paroi vertical polygonal (33) de la partie formation de rainure en forme de fente (32) du second élément d'électrode (30) est supérieure à celle de l'élément de paroi vertical (33) de la partie formation de rainure en forme de fente (22) du premier élément d'électrode (20).

6. Electrode composée d'usinage de matrice de moulage (10) selon l'une quelconque des revendications 1 à 5, dans laquelle la partie formation de rainure en forme de fente (22) du premier élément d'électrode (20) est formée des éléments de paroi verticaux hexagonaux (33), et la partie formation de rainure en forme de fente (32) du second élément d'électrode (30) est formée des éléments de paroi verticaux hexagonaux (33).

7. Procédé de fabrication d'une matrice de moulage pour mouler un corps moulé doté d'une circonférence externe circulaire ou elliptique par extrusion d'un matériau de moulage à travers des rainures en forme de fente, le procédé de fabrication comprenant les étapes suivantes :

la formation d'orifices d'alimentation sur une surface d'un substrat pour l'alimentation en matériau de moulage ; et

l'usinage des rainures en forme de fente communiquant avec les orifices d'alimentation sur le substrat au moyen de l'électrode composée d'usinage de matrice de moulage selon l'une quelconque des revendications 1 à 6.

8. Procédé selon la revendication 7, dans lequel l'usinage des rainures en forme de fente comprend :

une étape d'usinage de premières rainures en forme de fente pour usiner les rainures en forme de fente communiquant avec les orifices d'alimentation sur le substrat avec les éléments de paroi verticaux polygonaux (23) formés dans le premier élément d'électrode (20) ; et

une étape d'usinage de secondes rainures en forme de fente pour usiner sur le substrat les rainures en forme de fente, qui communiquent avec les orifices d'alimentation à l'extérieur des rainures en forme de fente usinées avec le premier élément d'électrode (20), avec les éléments de paroi verticaux polygonaux (33) formés dans le second élément d'électrode (30) de sorte que les rainures en forme de fente usinées avec la circonférence externe des éléments de paroi verticaux (33) du premier élément d'électrode (20) sont en chevauchement avec les rainures en forme de fente devant être usinées avec la circonférence interne des éléments de paroi verticaux (33) du second élément d'électrode (30).

9. Procédé selon la revendication 7, dans lequel l'usinage des rainures en forme de fente comprend :

une étape d'usinage de secondes rainures en forme de fente pour usiner les rainures en forme de fente communiquant avec les orifices d'alimentation sur le substrat avec les éléments de paroi verticaux polygonaux (33) formés dans le second élément d'électrode (30) ; et

une étape d'usinage de premières rainures en forme de fente pour usiner sur le substrat les rainures en forme de fente, qui communiquent avec les orifices d'alimentation à l'intérieur des rainures en forme de fente usinées avec le second élément d'électrode (30), avec les éléments de paroi verticaux polygonaux (23) formés dans le premier élément d'électrode (20) de sorte que les rainures en forme de fente usinées avec la circonférence interne des éléments de paroi verticaux (33) du second élément d'électrode (30) sont en chevauchement avec les rainures en forme de fente devant être usinées avec la circonférence externe des éléments de paroi verticaux (23) du premier élément d'électrode (20).

10. Procédé selon l'une quelconque des revendications 7 à 9, comprenant en outre les étapes suivantes :

l'usinage de la circonférence du substrat à une profondeur prédéterminée à partir de la surface du substrat et à une distance limite des rainures en forme de fente usinées avec le second élément d'électrode (30) après que les rainures en forme de fente ont été usinées le long de la circonférence la plus externe du substrat lors de l'étape d'usinage des rainures en forme de fente ; et

l'élimination des corps étrangers produits dans les rainures en forme de fente lors de l'étape d'usinage de la circonférence au moyen du second élément d'électrode (30).

Drawing